[PATCH] D76434: [SCEV] Query expanded immediate cost at minsize

[Sam Parker via Phabricator via llvm-commits]

samparker updated this revision to Diff 290902.
samparker added a comment.

Addressed comments.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D76434/new/

https://reviews.llvm.org/D76434

Files:
  llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp


Index: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
===================================================================
--- llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -2184,13 +2184,18 @@
 
   const T *S = cast<T>(WorkItem.S);
   int Cost = 0;
-  // Object to help map SCEV operands to expanded IR instructions.
+  // Object to help map SCEV operands to expanded IR instructions. For each
+  // operand of the SCEVExpr, in the given WorkItem, we will expand to one or
+  // more instructions. This struct holds the opcode of that instruction as
+  // well as the minimum and maximum operand indices that we should consider
+  // when expanding SCEVExpr, with an arbitary number of operands, to a chain
+  // of instructions.
   struct OperationIndices {
-    OperationIndices(unsigned Opc, size_t min, size_t max) :
-      Opcode(Opc), MinIdx(min), MaxIdx(max) { }
+    OperationIndices(unsigned Opc, int Min, int Max) :
+      Opcode(Opc), MinIdx(Min), MaxIdx(Max) { }
     unsigned Opcode;
-    size_t MinIdx;
-    size_t MaxIdx;
+    int MinIdx;
+    int MaxIdx;
   };
 
   // Collect the operations of all the instructions that will be needed to
@@ -2305,8 +2310,8 @@
   for (auto &CostOp : Operations) {
     for (auto SCEVOp : enumerate(S->operands())) {
       // Clamp the index to account for multiple IR operations being chained.
-      size_t MinIdx = std::max(SCEVOp.index(), CostOp.MinIdx);
-      size_t OpIdx = std::min(MinIdx, CostOp.MaxIdx);
+      int MinIdx = std::max((int)SCEVOp.index(), CostOp.MinIdx);
+      int OpIdx = std::min(MinIdx, CostOp.MaxIdx);
       Worklist.emplace_back(CostOp.Opcode, OpIdx, SCEVOp.value());
     }
   }
@@ -2341,15 +2346,13 @@
     : TargetTransformInfo::TCK_RecipThroughput;
 
   if (auto *Constant = dyn_cast<SCEVConstant>(S)) {
-    // Only evalulate the costs of constants when optimizing for size.
+    // Consider constants to be free unless we are optimizing for size.
     if (CostKind != TargetTransformInfo::TCK_CodeSize)
       return 0;
-    const APInt &Imm = Constant->getAPInt();
-    Type *Ty = S->getType();
     BudgetRemaining -=
       TTI.getIntImmCostInst(WorkItem.ParentOpcode, WorkItem.OperandIdx,
-                            Imm, Ty, CostKind);
-    return BudgetRemaining < 0;
+                            Constant->getAPInt(), S->getType(), CostKind);
+    return false;
   } else if (isa<SCEVCastExpr>(S)) {
     int Cost =
       costAndCollectOperands<SCEVCastExpr>(WorkItem, TTI, CostKind, Worklist);


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